Grafted network incorporating a multiple channel fluid flow connector

ABSTRACT

A grafted network including one or more graft segments for use in coronary bypass procedures and which are configured to operably transport bypass blood flow from a singular supply location to one or more delivery locations in the grafted network is provided in combination with one or more multiple channel blood flow connectors for directing such bypass blood flow in the grafted network to one or more vascular members requiring restorative blood flow thereto. The grafted network also preferably includes one or more devices for operably maintaining the grafted network under relatively high internal fluid pressure so as to continuously supply selective vascular members with adequate bypass blood flow.

FIELD OF THE INVENTION

The present invention relates to vascular graft networks generally, andmore particularly to coronary graft networks incorporating one or moregraft connectors that are specifically configured to efficientlytransport bypass blood flow from a source to one or more deliverylocations, which graft connectors may be directly implanted to thepatient's vasculature at specific designated bypass locations.

BACKGROUND OF THE INVENTION

Coronary bypass surgery has become a common procedure, and is normallyindicated for conditions requiring replacement and/or reconfigurationdue to blockage of the coronary blood flow within a patient. To achievesuch a bypass, grafts are surgically implanted to divert blood flow froma relatively high volume and pressure flow regime to a portion of thediseased vascular member downstream from the blockage therein. Intypical bypass procedures, a section of the vascular system in apatient's body that has become impaired or inoperative through diseaseor other defects may be treated so as to improve flow to those portionspreviously being supplied with an inadequate or limited supply of blood.In order to create the graft bypass, biocompatible graft material ispreferably employed, which graft material may be, for example, vascularmembers harvested from other portions of the patient's body or fromother animals, or biocompatible artificial materials such as, forexample, forms of polytetrafluoroethylene (commonly referred to asTeflon®).

While bypass procedures have been undertaken for some period of time,one particular and time consuming step is that of suturing the graftelements to respective portions of the patient's vasculature. Because ofthe physical properties of, in particular, artificial biocompatiblegraft material, suturing of such graft material is often times difficultto complete. The procedure is one which requires great dexterity, andwhen done at the site, is frequently in a zone with limitedaccessibility. Graft systems proposed to date have drawbacks with regardto ease of implantation and securement into the patient's vasculature.

An additional issue that is not satisfactorily addressed in existingbypass techniques is the inability of such techniques to effectivelymaintain flow and pressure from a blood flow source such as the aorta tothe vascular member in which the bypass procedure is conducted.Specifically, the blood supply stream is typically in a high-pressureflow environment, while the vascular member subject to bypass flow istypically a low-pressure blood flow environment. Accordingly, thesubstantial pressure drop between the respective bypass blood flowlocations generally results in low flow volumes to the artery or othervascular member to which bypass flow is directed. Previous attempts toprovide sustained flow volumes to respective vascular members from arelatively high pressure source have been met with limited success, inthat such systems proposed to date are difficult to manufacture andimplement, and particularly difficult to produce positive reproducibleimplantation results. In particular, such prior systems fail to providescomponents that may be quickly and effectively implanted in the surgicalprocess.

It is therefore a principle object of the present invention to provide agrafted network for consistently delivering sufficient blood flowvolumes to respective vascular members in a bypass procedure.

It is a further object of the present invention to provide a graftednetwork incorporating distinct connector means for effectivelychanneling bypass blood flow into respective vascular members whileminimizing damage to such vascular members and to such bypass bloodflow.

It is a yet further object of the present invention to provide a graftednetwork incorporating one or more graft segments in combination with oneor more distinct connector means for operably channeling bypass bloodflow into respective vascular members.

It is another object of the present invention to provide a graftednetwork incorporating a plurality of graft segments, one or moredistinct connector devices, and a flow restricting means for maintaininga desired level of blood flow pressure and volume through upstream graftsegments and such connector devices into respective vascular membersreceiving bypass blood flow thereto.

It is a still further object of the present invention to provide agrafted network which may be expediently surgically implanted within thepatient's body.

SUMMARY OF THE INVENTION

By means of the present invention, a grafted network is provided forenabling one or more coronary bypass procedures to be performed from asingle relatively high fluid pressure source location. In addition, thegrafted network of the present invention allows the bypass procedure tobe performed directly at particular sites in the targeted vascularmembers requiring bypass blood flow thereto, with each of the directsites being supplied with blood flow from a common singular bypass bloodflow stream. Moreover, the grafted network of the present inventionincludes means for maintaining the supply bypass blood flow stream athigh pressure while minimizing any turbulent flow effects through thegrafted network, so as to consistently provide adequate bypass bloodpressure and flow volume to each of the vascular members receiving suchflow.

In a particular embodiment of the invention, one or more graft segmentsconfigured to operably transport bypass blood flow from a singularsupply location to one or more delivery locations in a grafted networkare provided in combination with one or more multiple channel blood flowconnectors for directing such bypass blood flow in the grafted networkto one or more vascular members. The blood flow connectors areconfigured for coupling, for example, first and second graft segments toa first vascular member defining a first blood flow delivery location.The blood flow connector preferably includes a supply conduit and adelivery conduit integrally formed therewith and adjacently disposedwith respect to one another, with the supply conduit and the deliveryconduit each having a distinct lumen formed therewithin. The supplyconduit of the blood flow connector preferably includes first and secondopposed open ends having annular recessed portions and annular lips foroperably attaching respective open ends of the first and second graftsegments thereto. The supply lumen and the delivery lumen are fluidlyconnected to one another through cooperating apertures in respectiveouter walls of the supply conduit and the delivery conduit at anintersection therebetween so as to provide for immediate bypass bloodflow from the supply lumen to the delivery lumen. The delivery conduitincludes at least one open end portion extending from the intersectionand beyond an outer circumferential dimension of the supply conduitouter wall, such that a first open end of the delivery conduit islaterally spaced from, and extends beyond, the supply conduit outerwall. The delivery conduit is preferably configured for operableimplantation directly into the targeted vascular member so as to providebypass blood flow thereto. The delivery conduit is also preferablyspecifically sized to provide internal structural support for thetargeted vascular member when the delivery conduit is implanted therein.Such internal structural support is preferably provided without damageto the vascular member, as commonly occurs with stent devices.

In preferred embodiments of the present invention, a throttle device isprovided in the grafted network downstream from the most-downstreambypass location, and adjacent to the low pressure vessel or anatomicalsite. The throttle device is operably coupled to the grafted network andis disposed between the last blood flow connector and a terminaldelivery location for the grafted network of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a grafted network of the presentinvention employing a plurality of multiple channel blood flowconnectors.

FIG. 2 is a schematic view of certain elements of the grafted network ofthe present invention.

FIG. 3 is a front elevational view of a blood flow connector device ofthe present invention.

FIG. 4 is a bottom view of the connector device illustrated in FIG. 3.

FIG. 5 is a front elevational view of a throttle device of the presentinvention.

FIG. 6 is a side cross-sectional view of the throttle device illustratedin FIG. 5.

FIG. 7 is a partial cut-away view of a blood flow connector device ofthe present invention.

FIG. 8 is a partial cut-away view of a blood flow connector device ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects and advantages enumerated above together with other objects,features, and advances represented by the present invention will now bepresented in terms of detailed embodiments described with reference tothe attached drawing figures which are intended to be representative ofvarious possible configurations of the invention. Other embodiments andaspects of the invention are recognized as being within the grasp ofthose having ordinary skill in the art.

With reference to the enclosed drawing figures, and first to FIG. 1, agrafted network 10 includes a first graft segment 11 that is preferablyattached by suture to a relatively high-pressure blood flow environmentsuch as the aorta of a patient's heart, such as at location 12. Suchlocation 12 comprises a singular supply location for directing bloodthrough network 10 to one or more vascular members, such as coronaryarteries 14.

As illustrated in FIG. 1, first graft segment 11 is preferably securedto connector 13, which is described in greater detail hereinbelow.Connector 13 is preferably configured so as to direct a portion of theblood flow passing from supply location 12 and through first graftsegment 11 into a respective coronary artery 14. To accomplish thedesired channeling of at least a portion of the blood flow, connector 13preferably includes distinct conduits associated therewith, with atleast one of such conduits being implantable into the respectivevascular member, and particularly into coronary artery 14. Preferably, asecond graft segment 16 is operably coupled to a downstream side ofconnector 13, with connector 13 being configured to convey a portion ofthe blood flow within first graft segment 11 to second graft segment 16.In the embodiment illustrated in FIG. 1, second graft segment 16 isoperably coupled to a second connector 13A to thereby operably convey aportion of the blood flow within second graft segment 16 into a secondartery 14 to which second connector 13A is operably coupled.

In preferred embodiments of the present invention, grafted network 10further includes a third graft segment 18 which is operably coupled to adownstream end of second connector 13A so as to transport remainingblood flow therefrom. In some embodiments, third graft segment 18 isoperably coupled to a terminal delivery location 20 through suturing orthe like. Terminal delivery location 20 may be a vascular member, and ispreferably a relatively low pressure vessel or anatomical site such asan atrium or vena cava of the patient's heart. In preferred embodiments,however, and as illustrated in FIG. 2, a flow restricting means 22 isoperably disposed between terminal delivery location 20 and the finaland most downstream connector 13 in network 10. Flow restricting means22 is preferably a distinct throttle device that is secured within arespective grafted segment 18, and is configured to restrict the volumeof flow passing therethrough so as to maintain relatively higherpressure upstream therefrom. In addition, blood flow exiting flowrestricting means 22 is preferably at a relatively low fluid pressure soas to blend into the blood channels formed by the atrium or vena cavawithout excessive turbulent flow effects. Of course, graft segmentportion 24 which transports blood flow from a downstream end of flowrestricting means 22 to terminal delivery location 20, carries only thatblood which does not otherwise pass from network 10 to a respectivecoronary artery 14.

In some embodiments of the present invention, flow restricting means 22may be secured between adjacent grafted segments, with a first graftedsegment being operably coupled to a first open end of flow restrictingmeans 22, with a second graft segment being operably coupled to a seconddownstream open end of flow restricting means 22. In still furtherembodiments of the present invention, flow restricting means 22 may beintegrally formed within a respective graft segment 18, such that aportion of graft segment 18 includes a reduced internal diameter profileakin to that of flow restricting means 22. In such an embodiment, anentire workpiece may be formed through extrusion or other moldingprocesses to produce a single element having a flow restricting means 22integrally formed therewith.

Preferably, network 10 provides a means for efficiently performing oneor more bypass procedures with a modular apparatus having any desirednumber of vascular member connectors 13 and graft segments fluidlycoupling such connectors 13 to one another, as well as to at least asingular supply location 12, and preferably a terminal delivery location20. The respective graft segments of network 10 are preferablyfabricated from a biocompatible material that is somewhat elastic and iseasy to manipulate by the surgeon. A particularly preferred material foruse in manufacturing the graft segments is ePTFE, which is a form ofpolytetrafluoroethylene, and is widely known as a type of Teflon®material. The ePTFE segments are biocompatible, in that the body doesnot recognize such material as a “foreign” object, and therefore doesnot react negatively to its presence. Furthermore, the ePTFE material iscapable of being formed into tubing of substantially any desired size,and extruded to a desired degree of surface smoothness. Thebiocompatible characteristics minimizes the likelihood of clotformation, while the intra-wall porosity improves the endothelializationof the ePTFE. Though variants of polytetrafluoroethylene are mostdesired in forming the graft segments of the present invention, otherartificial or natural materials are also contemplated for use in thegraft segments. For example, vascular material harvested from apatient's own body, or vascular materials harvested from other livingbeings may be used as implantable graft segments in network 10. Aparticular disadvantage of utilizing vascular materials harvested frompatient's own body is that of additional recovery time and discomfortfor the patient as well as progressive vessel disease incurred as aresult of utilizing a vessel previously exposed to physiologicaleffects. Accordingly, artificial biocompatible materials are mostpreferred to minimize the degree of invasiveness into the patient toaccomplish the bypass procedures as to minimize the likelihood ofnatural blockage issues in the graft material.

As is best illustrated in FIG. 3, blood flow connector 13 is preferablya distinct unit having a plurality of blood flow channels for operablydirecting and channeling blood flow to pre-determined locations, mostpreferably into targeted vascular members. Blood flow connector 13includes a supply conduit 32 and a delivery conduit 34 integrally formedtherewith and adjacently disposed with respect to one another. Thoughblood flow connector 13 is presently shown and described as having asingle supply conduit and a single delivery conduit, variations of sucha design are also contemplated by the present invention. Namely, suchsupply and/or delivery conduits may be branched into a plurality ofdistinct conduits, or, alternatively, a plurality of individual supplyconduits and/or delivery conduits may be integrally formed in adjacentrelationship with one another in a single connector unit.

Supply conduit 32 includes at least first and second opposed open ends38, 40 which, in combination, define an axially extending supply lumen42 defined within the inner annular wall of supply conduit 32.Preferably, a respective graft segment 11 is operably secured to firstopen end 38 of supply conduit 32.

In preferred embodiments, supply conduit 32 includes annular recessedportions or grooves 46 disposed in an outer surface thereof and adjacentto respective open ends 38, 40. Such recessed portions 46 arespecifically configured to assist in obtaining a secure attachmentbetween respective graft segments and supply conduit 32. As illustratedin FIG. 3, annular recessed portions 46 provide a locating zone at whichto suture an open end of a respective graft segment therearound, in thatsuch sutures may circumferentially bind open ends of the respectivegraft segments to respective annular recessed portions 46. Furthermore,such annular recessed portions 46 define respective outer lips 48 atrespective open ends 38, 40 of supply conduit 32. In operation, suturescircumferentially retaining respective graft segments to annularrecessed portions 46 are further held axially in place by outer lips 48which create a friction fit with respect to the graft segments. Annularrecessed portions 46 and outer lips 48, in combination, collectivelyform coupling means for assisting in the graft sutures process to supplyconduit 32.

Delivery conduit 34 is preferably adjacently disposed to supply conduit32, and preferably is integrally formed with supply conduit 32. Supplyconduit 34 is preferably a hollow body, such that supply conduit 34contains a distinct supply lumen 52 therewithin. In some embodiments ofthe present invention, delivery conduit 34 includes coupling means 54akin to annular recessed portions 46 and outer lips 48. In otherembodiments of the present invention, however, coupling means 54 ondelivery conduit 34 includes an annular flange extension disposed aboutrespective end portions of delivery conduit 34.

Preferably, delivery conduit 34 includes at least one open end 56 andend portion 58 laterally extending beyond an outer circumferentialsurface of supply conduit 32, such that when end portion 58 is operablypositioned within a respective vascular member such as artery 14, thesurgeon may quickly and easily suture artery 14 to end portion 58without significant manipulation of connector 13, and withoutsubstantial interference from supply conduit 32 during the suturingprocess. In embodiments wherein delivery conduit 34 includes only oneopen end 56, all blood flow directed into the associated artery 14 exitsthrough open end 56, as indicated by arrow 60. In other embodiments ofthe present invention, delivery conduit 34 includes first and secondopen ends 56, 62, with second end 62 forming a portion of end portion64. Such embodiments are incorporated for applications in which bypassblood flow out from first and second end portions 58, 64 of deliveryconduit 34 is desired.

As is best illustrated in FIG. 4, supply conduit 32 and delivery conduit34 each include respective apertures 33, 35 disposed in integrallyadjacent outer walls, such that respective apertures 33, 35 intersectand superimpose with one another such that supply lumen 42 and deliverylumen 52 are fluidly coupled to one another. Specifically, bypass bloodflow entering first open end 38 of supply conduit 32 are transported inand through supply lumen 42, and to coordinating apertures 33, 35 ofsupply conduit 32 and delivery conduit 34. At least a portion of suchbypass blood flow accordingly passes through coordinating apertures 33,35, and correspondingly exits through one or more of open ends 56 and/or62 of delivery lumen 52. Preferably, respective apertures 33, 35 areintegrally formed with one another, so as to form a single unitaryaperture fluidly coupling supply lumen 42 and delivery lumen 52. Suchcoordinating apertures preferably include radiused edges so as tominimize stresses placed upon blood passing therethrough, as well as tominimize turbulent fluid flow effects. Cooperating apertures 33, 35, incombination, define an intersection between supply conduit 32 anddelivery conduit 34, with a central midpoint of such cooperatingapertures 33, 35 defining a central intersection plane 65 referred toherein.

Blood flow connector 13 is preferably fabricated from a biocompatiblematerial that is sufficiently strong and durable to withstand stressforces incorporated during implantation and eventually within thepatient's body. A particularly preferred material for use in blood flow13 is titanium, though a variety of other materials may be utilizedinstead. An alternative material for use in the fabrication of connector13 is a polytetrafluoroethylene such as ePTFE. In addition, otherbiocompatible materials not specifically stated herein are alsocontemplated as alternative materials for use in blood flow connector 13and/or flow restricting means 22.

As illustrated in FIGS. 1-2, connector 13 is preferably configured suchthat delivery conduit 34 may be directly implanted into a selectedportion of the patient's vasculature, and preferably adjacent to, anddownstream from, a blockage or other diseased portion of the particularvascular member. In such a manner, grafted network 10 may be implantedand surgically connected to the patient's vasculature directly, andwithout separate intravascular procedures. Therefore, the surgeon isable to create a distinct bypass (delivery) location in a selectedvascular member by making a relatively small incision thereto at theselected site. The surgeon is then able to manipulate connector 13 so asinsert delivery lumen 34 within the respective vascular member for bloodconduction thereto. It is a particularly preferred aspect of the presentinvention to provide delivery conduit 34 with an outer dimension of asize similar to the internal diameter of the particular vascular memberin which the bypass procedure is being conducted. Preferably, deliveryconduit 34 is within about +/−20% of the corresponding inside diameterof the associated vascular member. The particular sizing described abovewith respect to delivery conduit 34 is preferred so as to obtain a snugfriction fit between delivery conduit 34 and the associated vascularmember. Due to the somewhat elastic nature of vascular members withinthe human body, it is desired to size substantially fixed-dimensionelements of at least connector 13 similar to the corresponding vascularmembers so as to achieve a fluid-tight tissue fit connectiontherebetween. Such a fitment assists in permanently affixing thevascular member to grafted network 10 in addition to the suturessecuring such vascular members to grafted network 10. Moreover, deliveryconduit 34 is preferably a size so as to provide internal structuralsupport to the corresponding vascular member when implanted therein. Insome procedures, a separate and distinct expandable orfixed-configuration stent device is implanted into the vascular memberin order to provide structural support to the vascular member after itsstructure has been compromised by a medical procedure performed thereon.Typical stent devices create substantial expansive forces on therespective vessel walls and in some cases generate excessive internalpressure on the vessel. Accordingly, delivery conduit 34 of the presentinvention acts both as a means for directing blood flow from graftednetwork 10 into a particular vascular member, as well as to structurallysupport such vascular member from therewithin without excessivelystraining the respective vessel wall. Such structural support operablymaintains the associated vascular member in an open orientation andsubstantially prevents collapse thereof at the implantation location.

The foregoing description of the configuration and sizing of deliveryconduit 34 may also be incorporated into supply conduit 32 for apreferred selected securement to respective graft segments. As indicatedabove, the preferred ePTFE material making up the respective graftsegments is somewhat malleable in nature, and can therefore beconfigurationally modified by the surgeon during the implantationprocedure. Preferably, respective open ends of the graft segments beingoperably secured to supply conduit 32 are modified with anappropriately-sized tool or a manual rolling manipulation that enlargesthe inside diameter of an end portion of the respective graft segmentsbeing fitted onto respective ends on supply conduit 32. In such amanner, latent restorative forces within the respective graft segmentsact to compress upon respective outer surfaces of supply conduit 32, soas to obtain a snug connection thereto.

In preferred embodiments of the present invention, one or morecomponents of the apparatus of the present invention may be coated on atleast inner surfaces thereof with biocompatible material or made ofmixed biocompatible material to further reduce any biologicalincompatibility issues. In particular, such biocompatible and/or drugeluting coatings are preferably disposed on at least inner surfaces ofconnector 13, though such biocompatible coatings may be placed upon anyor all surfaces of grafted network 10. A particular biocompatiblecoating contemplated for use in the present invention includes amulti-layer biocompatible coating including silane, polyvinylpyrrolidine(PVP), heparin, and a photo-reactive cross-linking agent. In particular,a first layer contains isopropylalcohol (IPA), a second layer having ahydrophilic material such as PVP and IPA, and a third layer having PVPand heparin. Such a biocompatible coating is for exemplary purposesonly, and does not restrict the present invention from utilizing a widevariety of biocompatible coatings on inner and outer surfaces ofrespective components of the present invention. For example, carboncoatings may be utilized on bio-compatible as well as non bio-compatiblecomponents of the present invention through vapor deposition or otherknown coating processes.

Other biocompatible materials may be utilized for various elements ofthe present invention, including certain mixed or co-extruded materials.A particular example of a co-extruded biocompatible material useful inrespective components of the present invention is co-extruded resins ofePTFE and carbon. In addition, pyrolytic carbon may be utilized as abiocompatible material in such components.

As shown in FIG. 9, at least first end 38 of supply conduit 32 ispreferably tapered such that the thickness of supply conduit 32 at firstend 38 is less than about 50% of the thickness of central portion 31 ofsupply conduit 32. Such a tapered end is an important aspect of thepresent invention, and is specifically configured for reducing flowstresses on the fluid, as well as minimizing imposition of turbulentflow characteristics to the fluid flow stream. By minimizing sucheffects, the blood flow passing through connector 13 is less likely tobe damaged and/or to coagulate or clot, which could potentially pose ahealth threat to the patient. Accordingly, the tapered configuration ofthe present invention specifically enables smooth flow transitions fromrespective graft segments into, and through connector 13, as well aseventually into the respective vascular members of the patient. Inaddition to tapering first end 38 of connector 13, the present inventioncontemplates tapering second end 40 of supply conduit 32, as well asopen ends of delivery conduit 34 and flow restricting means 22. Variouscombinations of tapered ends of respective components of the presentinvention may be utilized as desired.

An additional aspect of the present invention for assisting andminimizing potentially deleterious effects to blood flow passing throughvarious components of network 10 is in the preferred surface finishingof, in particular, flow connector 13. Specifically, the surface finishof at least inner surfaces of connector 13, and preferably of flowrestricting means 22, is about 20-30 μinches, and more preferablybetween about 24 and about 28 μinches. The above-stated level of surfacesmoothness is advantageous in the present invention for minimizinghemolysis in the blood flow passing therethrough.

As is illustrated in FIG. 2 and in FIGS. 5-6, grafted network 10preferably includes a flow restrictor means 22 having a contoured innerdiameter so as to obtain a throttling effect to fluid passingtherethrough. The contoured inner dimension of flow restricting means 22is shown in dashed lines in FIG. 2, and is best represented in thecross-sectional view of FIG. 6. Flow restricting means 22 is preferablya distinct unit having an outer surface 25 and an open channel 26axially extending therethrough. Flow restricting means 22 furtherincludes first and second ends 27, 28, with flow being directed throughrestricting means 22 from first end 27 through second end 28.Preferably, flow restricting means 22 includes a converging taperedportion 92 extending from a first end portion 29 to a central throttleportion 94. As shown in FIG. 6, central throttle portion 94 extendsbetween converging inlet tapered portion 92 to diverging outlet taperedportion 96, which diverging outlet taper portion 96 extends to secondend portion 30 of flow restricting means 22. Although flow restrictingmeans 22 is described as having “tapered” portions for providing desiredflow characteristics, the present invention contemplates a variety ofinlet portion and outlet portion configurations including parabolic orother formations, so long as inlet portion 92 includes a converginginner diameter, and outlet portion incorporates a diverging innerdiameter for flow restricting means 22.

The inner diameter configuration through flow restricting means 22 ispreferably designed so as to create a substantial flow pressure decreasebetween inlet end 27 and outlet end 28, as well as to create substantialback pressure into grafted network 10 upstream from flow restrictingmeans 22. Such objectives are accomplished by reducing the diameterthrough which fluid flow may pass as it exits grafted network 10.However, it is preferred that the flow restricting means enable suchpressure characteristics while maintaining a substantially laminar flowregime throughout flow restricting means 22. Accordingly, the innerdiameter profile of flow restricting means 22 is specifically configuredso as to maximize pressure drop therethrough while maintainingsubstantially laminar flow regime. In particular, inlet taper portion 92is tapered between about 30° to about 40° with respect to a central axis99 of flow restricting means 22, and more preferably between about35°-40°. Outlet diverging taper portion 96 of the present invention ispreferably angled between about 10° and about 20° with respect to axis99, and more preferably about 12°-15° with respect to axis 99. Disposedbetween such inlet taper portion 92 and outlet taper portion 96 isthroat portion 94, which is a substantially constant-diameter section ofopen channel between about 1.5 to about 2.0 mm, and more preferablybetween about 1.6 and about 1.8 mm in diameter. In other embodiments ofthe present invention, however, throat portion 94 may be somewhatconvergent or divergent in inner diameter, or both, such that none oronly a portion of throat portion 94 is a constant diameter.

In preferred embodiments of the present invention, fluid flow passingthrough flow restricting means 22 loses between about 90 and 95% of theenergy initially carried by the fluid upon exit from source location 12.Accordingly, flow restrictor means 22 creates a substantial pressuredrop from inlet 27 to outlet 28, thereby effectively maintaining aconstant fluid pressure in network 10 upstream from flow restrictingmeans 22, which pressure is substantially equal to the fluid flowpressure within the relatively high fluid pressure source. In otherwords, the relatively high fluid pressure to relatively low fluidpressure network provided by flow restrictor means 22 of the presentinvention enables network 10 to maintain relatively high fluid flowthroughout the system. Accordingly, the one or more vascular membersbeing supplied with bypass blood flow are insured of having adequatesource flow from network 10 to satisfy the needs of the particularvascular member.

In some existing systems for bypass procedures, graft segments areutilized to directly couple an aortic blood source to a respectivevascular member requiring bypass blood flow thereto. Due to thegenerally low pressure environment of the arteries receiving bypassblood flow, blood is not typically supplied under pressure throughoutthe graft segment. As such, bypass blood flow into the respectivearteries can be less than adequate due to the low fluid pressure withinthe graft segment. By contrast, network 10 of the present invention ismaintained under relatively high pressure due to the specificallyconfigured flow restraining means 22. Accordingly, bypass blood flow isimmediately available to respective vascular members 14 throughconnectors 13 when needed. An additional advantage inherent in network10 of the present invention is due to the relatively high fluid pressuremaintained therewithin. In many current systems, stand-alone graftsegments must be spirally reinforced to maintain a predeterminedconfiguration, particularly during times of relatively low internalfluid pressure. Since the respective graft segments of network 10 of thepresent invention are consistently maintained at relatively highinternal fluid pressure, no spiral reinforcement of respective graftsegments is required herein. Accordingly, the thickness, and thereforeworkability and malleability, of the graft segment material may besignificantly reduced. Moreover, such reduced thickness graft materialfurther results in cost savings over conventional systems.

As described above, flow restricting means 22 may preferably includeannular recessed portions 102 disposed on an outer surface thereofadjacent to first and second ends 27, 28. Such annular recessed portionsact as locating means for assisting a technician in securing flowrestricting means within a respective graft segment by providinglocations at which sutures or other securing means may be fixedlypositioned. Flow restricting means 22 is preferably a distinct body thatis operably positioned and secured within a respective graft segment,such as graft segment 18, at a location adjacent to terminal deliverylocation 20. The distinct body of flow restricting means 22 may beselectively positioned at desired locations within a respective graftsegment, such that network 10 is modifiable for particular implantationprocedures.

In other embodiments of the present invention, open ends of respectivegraft segments are coupled to first and second ends 27, 28 of flowrestricting means 22. Such graft segment ends may preferably be expandedoutwardly with the use of a tool having a specific predetermineddiameter or a rolling manual manipulation, such that the resultinginternal diameter of respective open ends of the graft segments coupledto flow restrictor means 22 through a snug interference fit. Of course,such graft segments are permanently secured to first and second ends 27,28 of flow restricting means 22 through sutures or other permanentattaching means, such as glue or the like.

In still further embodiments of the present invention, flow restrictingmeans 22 may be integrally formed with a respective graft segment, inthat the graft segment and flow restricting means 22 share commonmaterials and outer surfaces. In such an embodiment, the respectivegraft segment is provided as being substantially longer than isnecessary in typical implantation procedures, such that the surgeon maycut the length of the unit to properly fit within network 10 of thepresent invention.

Flow restricting means 22 is preferably fabricated from a biocompatiblematerial such as ePTFE, but may instead be fabricated from other durableand biocompatible materials, including certain metals. In addition, flowrestricting means 22 may include one or more biocompatible coatingsdisposed on at least inner surfaces thereof for enhancing itscompatibility within the body of a patient.

Additional embodiments of multiple channel fluid flow connectors of thepresent invention are illustrated in FIGS. 7-8. As shown in FIG. 7, flowconnector 112 includes a supply conduit 114 and a delivery conduit 116,with supply conduit 114 and delivery conduit 116 being coupled viaintermediate conduit 118. Preferably, intermediate conduit 118 forms anopen passageway between supply conduit 114 and delivery conduit 116 suchthat supply conduit 114 and delivery conduit 116 are fluidly coupled toone another via intermediate conduit 118. Preferably, intermediateconduit 118 includes radiused transition points forming flared ends 120,122 for transporting blood flow therethrough with minimal deleteriouseffects thereon. In particular, flared ends 120, 122 extend outwardlyfrom an annular apex 121, 123 to respective annular outer ends 129, 130,with such annular outer ends 129, 130 having a diameter exceeding thediameter of transfer conduit 118 by between about 0.25 and about 1.5 mm.Such a configuration minimizes turbulent flow effects, as well astransitional corners where damage to blood may occur.

A further alternative embodiment is illustrated in FIG. 8, whereintransfer conduit 148 is angled with respect to supply conduit 144 in anorientation such that an obtuse angle α of between about 100° and 120°is formed between transfer conduit 148 and first inlet open end 145 ofsupply conduit 144. Correspondingly, an acute angle β of between about60° and about 80° is formed between transfer conduit 148 and secondoutlet end 146 of supply conduit 144. In the embodiment illustrated inFIG. 8, transfer conduit 148 is so angled such that in-flow of fluid isat least partially directed into delivery conduit 150 through transferconduit 148 without having to undergo a substantially right-angle flowtransition. Thus, fluid flow passing through transfer conduit 148undergoes a reduced degree of stress imparted thereon to reach deliveryconduit 150.

An additional alternative embodiment of the present invention isillustrated in FIG. 10, and shows a flared outer end of transfer conduit178. Such a flared outer end 180 assists in minimizing turbulent floweffects as blood flow is routed from supply conduit 176 into thetargeted vascular member via transfer conduit 178.

Referring back to FIGS. 3 and 4, first end portion 58 may be somewhatlonger than second end portion 62, and may be between about 1 and 4 mmlonger than second end portion 62. Such a configuration assists thesurgeon in inserting delivery conduit 34 into the targeted vascularmember 14 by reducing the incision size into vascular member 14. Inoperation, the surgeon may insert relatively longer end portion 58 intovascular member 14, and then simply “drop” second end portion 62 thereinfor complete insertion. In other embodiments of the present invention,second end portion 62 may be relatively longer than first end portion58, as measured from intersection plane 65.

In some embodiments of the present invention, at least delivery conduit34 is fabricated from a selectively expansive material, such that whendelivery conduit 34 is implanted within a particular vascular member 14,the diametrical dimension thereof may be selectively expanded so as toobtain a fluid-tight interference fit within the respective vascularmember 14. Such a selectively expansive material may be in a meshconfiguration, and may be, for example, nitanol. Other components of thepresent invention may also or instead be fabricated from a selectivelyexpansive material.

An additional embodiment of the present invention provides for arotation means disposed between supply conduit 32 and delivery conduit34, wherein delivery conduit 34 may be selectively rotated with respectto supply conduit 32, whereby specific alignment between network 10 anda particular vascular member 14 is less critical, due to the fact thatdelivery conduit 34 may be rotated into alignment with such vascularmember 14 without disturbing grafted network 10.

In preferred embodiments of the present invention, supply conduit 32 isbetween about 2 mm and about 8 mm in external diameter, and deliveryconduit 34 is between about 0.5 mm and about 5 mm in external diameter.In a particularly preferred embodiment of the present invention, supplyconduit 32 has an external diameter of about 6 mm, and delivery conduit34 has an external diameter of about 3 mm.

In accordance with the present invention, one or more graft segments areprovided for each bypass procedure. In addition, at least one multiplechannel fluid flow connector is provided comprising biocompatiblematerial and includes an integrated supply conduit and delivery conduitfor channeling blood flow from a relatively high pressure source to alocation in, for example, a coronary artery where blood flow correctionis needed. The connector devices are typically dual-lumen which providesfor direct channeling from the supply conduit to the delivery conduit,and consequently to the targeted vascular member. In the dual-lumenstructure of the present invention, a relatively large diameter lumen isemployed for that portion of the connector device which is in directcommunication with the aortic or other high pressure source, and withthe delivery lumen typically being of somewhat lesser overall diameterand being designed for insertion into a slit formed in the targetedvascular member requiring bypass.

In preferred embodiments of the present invention, at least one graftsegment is pre-attached to an open end of connector 13, and is of alength which is more than ample for the contemplated use. For example,first graft segment 11 is preferably pre-attached to first end 38 ofsupply conduit 32 prior to surgery, and preferably prior to shipmentfrom the manufacturing facility. First graft segment 11 is consequentlymade substantially longer than necessary for connection between vascularmember 14 and source location 12, such that the surgeon may cut firstgraft segment 11 to size during the surgical process. Thus, the surgeonis able to cut the graft segment to a desired and required length in thecourse of the procedure, while at the same time not having to disturbthe integrity of the previously-prepared secure junction between firstgraft segment 11 and connector 13.

In the course of the overall procedure, terminal end 20, including graftsegment 24, are secured in place at the vena cava or other low-pressuresite, while continuing the process in the direction of the source, whichis normally the aorta. Attachments are made in accordance withconventional protocol, with connector 13 being coupled through a slitformed in the pertinent vascular member to provide bypass flow thereto.

The invention has been described herein in considerable detail in orderto comply with the patent statutes, and to provide those skilled in theart with the information needed to apply the novel principles and toconstruct and use embodiments of the invention as required. However, itis to be understood that the invention can be carried out byspecifically different devices and that various modifications can beaccomplished without departing from the scope of the invention itself.

1. In combination with one or more graft segments configured to operablytransport bypass blood flow from a singular supply location to one ormore delivery locations in a grafted network, means for directing suchbypass blood flow in said grafted network to one or more vascularmembers, said means comprising: a multiple channel blood flow connectorfor coupling first and second graft segments to a first vascular membercomprising a first blood flow delivery location, said flow connectorincluding a supply conduit and a delivery conduit integrally formedtherewith and adjacently disposed with respect to one another, with saidsupply conduit and said delivery conduit each having distinct lumenformed therewithin, said supply conduit having first and second opposedopen ends having coupling means for operably attaching respective openends of such first and second graft segments thereto, said supply lumenand said delivery lumen being fluidly connected to one another throughcooperating apertures in respective outer walls of said supply conduitand said delivery conduit at an intersection therebetween so as toprovide for immediate bypass blood flow from said supply lumen to saiddelivery lumen, said delivery conduit having at least one open endportion extending from said intersection and beyond an outercircumferential dimension of said supply conduit outer wall, such that afirst open end of said delivery conduit is laterally spaced from saidsupply conduit outer wall, said delivery conduit being configured foroperable implantation directly into the first vascular member so as toprovide bypass blood flow thereto, said delivery conduit beingspecifically sized to provide internal structural support for the firstvascular member when said delivery conduit is implanted therein.
 2. Ameans as in claim 1 wherein said first and second open ends of saidsupply conduit are tapered such that the thickness of said supplyconduit outer wall at said first and second open ends is less than about50% of the thickness of said supply conduit outer wall at locationsbetween said first and second open ends.
 3. A means as in claim 1wherein at least said first open end of said delivery conduit is taperedsuch that the thickness of a delivery conduit outer wall at said firstopen end is less than about 50% of the thickness of said deliveryconduit outer wall at locations between said first open end and saidintersection.
 4. A means as in claim 1 wherein said supply conduit andsaid delivery conduit are in integrally adjacent relationship with oneanother.
 5. A means as in claim 1 wherein said cooperating apertureshave radiused edges.
 6. A means as in claim 1 wherein inner surfaces ofsaid supply conduit and said delivery conduit are polished to a surfacesmoothness of about 26 μinches.
 7. A means as in claim 1 wherein thefirst graft segment is operably coupled to the blood flow supplylocation and said first open end of said supply conduit of said flowconnector, and a first end of the second graft segment is operablycoupled to said second open end of said supply conduit of said flowconnector.
 8. A means as in claim 7, including a flow restricting meansdisposed downstream from said flow connector and operably coupled tosaid grafted network adjacent a terminal delivery location thereofopposite the supply location.
 9. A means as in claim 8 wherein said flowrestricting means includes first and second open ends operably coupledto respective graft segments in said grafted network, with one of saidrespective graft segments extending between said flow restricting meansand said terminal delivery location.
 10. A means as in claim 9 whereinsaid blood flow supply location is an aorta, and said terminal bloodflow delivery location is an atrium or vena cava of a patient.
 11. Ameans as in claim 1, including one or more biocompatible coatings on atleast inner surfaces of said flow connector.
 12. A means as in claim 8,including one or more biocompatible coatings disposed on at least innersurfaces of said flow restricting means.
 13. A means as in claim 11wherein at least one of said biocompatible coatings comprises silane,polyvinylpyrrolidine, heparin, and a photo-reactive cross-linking agent.14. A means as in claim 12 wherein at least one of said biocompatiblecoatings comprises silane, polyvinylpyrrolidine, heparin, and aphoto-reactive cross-linking agent.
 15. A means as in claim 1, includinga biocompatible coating disposed on at least inner surfaces of selectedgraft segments.
 16. A means as in claim 1 wherein said delivery conduitincludes a second end portion having a second end, with said second endportion extending from said intersection in a direction divergent fromsaid first end portion of said delivery conduit.
 17. A means as in claim16 wherein said first end of said delivery conduit is open, and saidsecond end is closed.
 18. A means as in claim 16 wherein said first andsecond ends of said delivery conduit are open.
 19. A means as in claim 1wherein said supply conduit has an external diameter of up to about 8 mmand said delivery conduit has an external diameter of up to about 5 mm.20. A means as in claim 1 wherein said first end portion of saiddelivery conduit is at least 1 mm longer than said second end portion ofsaid delivery conduit as measured from said intersection.
 21. A means asin claim 1, including a transfer conduit interconnectably disposedbetween said supply conduit and said delivery conduit, said transferconduit fluidly extending between respective said cooperating aperturesin said supply conduit and said delivery conduit, said transfer conduithaving first and second opposed open ends, at least one of said openends being flared outwardly from an annular apex to an annular outerend, said annular outer end having a diameter exceeding the outerdiameter of said transfer conduit by between about 0.25 and 1.5 mm. 22.A means as in claim 21 wherein said transfer conduit is angled withrespect to said supply conduit of said flow connector in an orientationsuch that an obtuse angle of at least about 100° is formed as delineatedbetween said transfer conduit and said first open end of said supplyconduit which receives blood flow from the supply location, andcorrespondingly an acute angle of less than about 80° is formed betweensaid transfer conduit and said second open end of said supply conduit ofsaid flow connector.
 23. A means as in claim 1 wherein at least saiddelivery conduit is formed from a selectively expansive material forproviding an interference fit between said delivery conduit and thevascular members sufficient to assist in forming a liquid-tight sealtherebetween.